Tetracarboxylic acid combinations for corrosion inhibition
a technology of tetracarboxylic acid and corrosion inhibition, which is applied in the direction of chemical inhibitors, chemical apparatus and processes, organic chemistry, etc., can solve the problems of phosphorus under environmental pressure and may only be used in very low-level quantities, localized corrosion (e.g. pitting) may pose an even greater threat to the normal operation of the system, and the structural integrity of the system or structure deterioration
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example 1
of BTCA
[0061]A synthesis according to Scheme 1 was performed. A 250 ml round-bottomed flask equipped with a magnetic stirring bar and a reflux condenser was charged with 0.2167 g (0.0657 mmol) of sodium tungstate (Na2WO4). Water and 32.8 g (0.289 mol) of aqueous 30% hydrogen peroxide (H2O2) was added. The mixture was vigorously stirred at room temperature for 10 min and then 10 g (0.0657 mol) of 3a,4,7,7a-tetrahydroisobenzofuran-1,3-dione (Compound 1) was added. The mole ratio of Compound 1:H2O2:Na2WO4 was 1:4.4:0.01. The biphasic mixture was heated successively at 75° C. for 30 min, at 80° C. for 30 min, at 85° C. for 30 min, and at 90° C. for 6.5 hours, with vigorous stirring. The homogeneous solution was cooled down and collected for analysis.
[0062]
[0063]After the reaction the content of BTCA was measured in the reaction mixture using high pressure liquid chromatography (HPLC). The weight percent of BTCA was 24% and the byproduct tetrahydrophthalic acid (THPA is Compound 2 in Sch...
example 2
of BTCA
[0064]A 250 ml round-bottomed flask equipped with a magnetic stirring bar, a reflux condenser and connected with paraffin oil trap was charged with 0.432 g of Na2WO4, water, and 65 g of aqueous 30% H2O2. The mixture was vigorously stirred at room temperature for 10 min and then 20 g of Compound 1 was added. The mole ratio of Compound 1:H2O2:Na2WO4 was 1:4.4:0.01. The biphasic mixture was heated up to 90° C., a high exotherm was observed at −50° C. with high oxygen evolution, which ceased after a few seconds. The homogeneous solution was cooled down and collected for analysis.
[0065]After completing the steps above, samples were taken of the reaction mixture to determine the content of BTCA and THPA using HPLC. The weight percent of BTCA in the reaction mixture was 33.1% and the weight percent of THPA was less than 1%.
example 3
of BTCA
[0066]A 250 ml round-bottomed flask equipped with a magnetic stirring bar, a reflux condenser, and connected with paraffin oil trap was charged with 0.432 g of Na2WO4, water, and 65 g of aqueous 30% H2O2. The mixture was vigorously stirred at room temperature for 10 min and then 20 g of Compound 1 was added. The biphasic mixture was heated. A high exotherm was observed at −50° C. with high oxygen evolution, which ceased in few seconds then reaction mixture again heated for 8 hours at 90° C. The homogeneous solution was cooled down and collected for analysis.
[0067]An NMR sample was prepared by dissolving the powder in D2O. Quantitative proton spectra were used to quantize the mole % of each component. Total Correlation (TOCSY) and Heteronuclear single quantum coherence (HSQC) spectra were acquired to characterize the structures of major components. The stacked proton spectra of BTCA at 5.5 hr and 8 hr appeared almost identical. The TOCSY spectrum of sample at 5.5 hr suggested ...
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